Need pricing information

I have a Craftsman graden tractor I bought in 2000. I kept it last year thinking I might use it for something, but I didn't. The deck is only two years old. It has a 50 in. deck with a 20 horse Kohler engine. I want to sell it. I have no clue what to ask for it. Any suggestions? It is in good shape. With the addition of my JD z-track, the Craftsman is collecting dust. And, yes, I know most of you on here hate Craftsman lawn mowers, but it did serve its purpose until I could afford a newer and nicer piece of equipment, so serious replies would be appreciated. Thanks.